Transvinylation or vinyl interchange technology has existed for several decades. The reaction can be illustrated by the reaction of a vinyl ester or vinyl ether with an active hydrogen containing compound, as in the following: ##STR1## wherein R is carboxy, amido, aroxy, alkoxy, and the like; X is hydrogen, hydroxyl, alkyl, aryl, and the like; and R' is carboxyl, amido, alkyl, substituted alkyl, aryl or substituted aryl.
Adelman, Journal Organic Chemistry, 14, pp. 1057-1077, 1949, at p. 1057, termed transvinylation "the `Vinyl Interchange` Reaction, to differentiate it from typical ester interchange and ester-acid interchange reactions" . . . Adelman noted the following advantages for this reaction:
"The very mild reaction conditions and the low yields of by-products lead to high yields of monomers of greater purity and activity than those prepared by the reaction of acetylene with acids." PA1 "Furthermore, vinyl esters of dibasic acids are prepared much more easily by vinyl interchange than through the acetylene route, and recent work in this laboratory has shown that the reaction of vinyl acetate catalyzed with mercuric salts is not restricted to carboxylic acids, but will occur with other compounds containing active hydrogen, such as acetoacetic ester and glycolic esters." PA1 a vinyl derivative of a Bronsted acid; PA1 a different Bronsted acid with which to interchange; PA1 a ruthenium compound; and PA1 liquid phase reaction conditions.
McKeon, et al., Tetrahedron, 28, pp. 227-232 (1972) show the vinyl interchange reaction between a vinyl ether and an alcohol using a palladium catalyst. Other sources report the transvinylation reaction between vinyl chloride and a carboxylic acid.
The literature suggests that the preferred catalysts for transvinylation reactions have been mercury and palladium based compounds. However, Pt (II) and Rh (III) have been reported by A. Sabel, J. Smidt, R. Jira and H. Prigge, Chem. Ber., 102, pp. 2939-2950 (1969), to catalyze the reaction. In addition, Young, U.S. Pat. No. 3,755,387, patented Aug. 26, 1973, entitled: "A Vapor Phase Transvinylation Process", claims the use of supported Hg, Pd, Pt, Ir, Rh, Ru, or Os salt catalysts in a vapor phase transvinylation process. The experimental portion discloses the use of only palladium on carbon, copper on carbon, iron on carbon, palladium/copper on carbon, palladium/copper/iron on silica, mercuric acetate on carbon, and mercuric chloride on carbon. Hg and Pd are cited, at col. 1, line 67, as the preferred metals. There is no recognition by this patentee of any special advantages to (i) the use of ruthenium compounds as catalysts for transvinylation reactions and (ii) effecting the reaction in a liquid phase reaction using a ruthenium compound as the catalyst.
Significant deficiencies in these prior art technologies are:
1. The mercury-based catalyst is toxic, undesirably volatile, and is typically activated with sulfuric acid to promote reaction and then deactivated by neutralization with base prior to product distillation. Traces of adventitious free acid generated by this system tend to promote ethylidene diester formation. PA0 2. Palladium-based catalysts are not sufficiently thermally stable to allow product removal by distillation at elevated temperatures; the catalyst often deactivates forming metallic Pd.
M. Rotem, et al., Organometallics, 2, pp. 1689-1691 (1983), T. Mitsudo, et al., J. Org. Chem., 50, pp. 1566-1568 (1985), and T. Mitsudo, et al., J. Org. Chem., 52, pp. 2230-2239 (1987) show the use of ruthenium based catalysts to promote the addition of carboxylic acids to alkynes and producing alkenyl carboxylates. In particular, the reaction of carboxylic acids with substituted alkynes is facile. The reaction of carboxylic acids with acetylene (vinylation) to give vinyl esters is also possible, but at a much slower rate. Various catalyst precursors have been studied which include ruthenium carbonyl, bis(eta 5-cyclooctadienyl)ruthenium (II)/tri-n-butylphosphine, and bis(eta 5-cyclooctadienyl)ruthenium (II)/trialkylphosphine/maleic anhydride.
The use of these and similar ruthenium compositions as transvinylation catalysts has apparently not been recognized until this invention. The beneficial use of ruthenium-containing compounds as catalysts for transvinylation processes which overcome several of the deficiencies noted for the prior art catalysts has not been appreciated until this invention.
There is a need in the transvinylation art for a catalyst having high catalytic activity at convenient elevated temperatures which would allow the facile removal of the desired product of the reaction without interfering with other components present in the reaction product mixture.